Food Technology
Elham Ahmadi; Sara Panahi; Amirhossein Karimzadeh; Hamed Hassanzadeh; Mohammadyar Hosseini
Abstract
IntroductionIn recent years, with increasing concerns about food safety and environmental issues related to waste generated by non-degradable plastic packaging, study on novel biodegradable packaging materials has attracted the attention of researchers. Active packaging based on biopolymers, which offers ...
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IntroductionIn recent years, with increasing concerns about food safety and environmental issues related to waste generated by non-degradable plastic packaging, study on novel biodegradable packaging materials has attracted the attention of researchers. Active packaging based on biopolymers, which offers a sustainable and environmentally friendly way to improve food shelf life, considered one of such packaging technologies. Edible coatings and films, are a thin layer of edible compounds and biopolymers applied on the surface of foodproducts that play important role to control physicochemical, microbial and physiological changes in food. Gelatin is obtained from partial degradation of collagen. Due to its availability, relatively cheap price, biodegradability and good properties such as its excellent ability to form a film and reduce the transfer of oxygen, oil and moisture, it is highly regarded as an edible film and has antimicrobial and antioxidant activity. In general, the gelatin film showed high water absorption due to the presence of several hydrophilic groups, which may weaken the mechanical properties and water vapor transport of the film. For this reason, the combination of gelatin with other biopolymers such as chitosan, starch and gum is a suitable method to eliminate the drawbacks of gelatin-based films.Materials and MethodsTo prepare the composite film of the four formulations studied in this research, gelatin powder (3% by weight/volume of water) and glycerol (30% by weight/volume of gelatin powder) were added to deionized water and magnetically stirred for 10 minutes at 2400 RPM. To prepare an aqueous suspension of carboxymethyl cellulose, powder (CMC 2% by weight/volume of water) and glycerol (30% by weight/weight of carboxymethyl cellulose powder) were mixed with deionized water. This suspension was heated to boiling temperature and kept at this temperature for 15 minutes and then kept for 30 minutes at 90°C water bath and stirred. The G/CMC coating was also prepared by dissolving 40 grams of gelatin, 10 grams of carboxymethyl cellulose and glycerol (30% by weight/weight of polymer materials) in one liter of water. The mixture was stirred for 1 hour at 60 degrees Celsius. The mixture was then dried at 25-35 degrees Celsius. Different concentrations of the extract (0, 0.5, 0.75, 1.5 and 3.25%) were added to the mixture and stirred for 2 minutes. In the next step, the mixture was added to a plastic Petri dish with a diameter of 15 cm and placed under a vacuum hood for 1 hour. Then it was transferred to a fan oven and kept for 20 hours. In the final stage, the dried films were placed in a desiccator at room temperature for testing. The effect of different concentrations of Dorema aucheri extract for the production of edible films on the physicochemical, mechanical, antioxidant and antimicrobial properties was analyzed with one-way analysis of variance (ANOVA) and comparing the average data was performed based on Duncan's multi-range test using SPSS26 software at probability level of 0.05.Results and DiscussionThe highest tensile strength and elongation at break point and Young's modulus in the treatment was 1.5%. In all concentrations, solubility and permeability were significant (p<0.05). The lowest solubility was observed in the control. The highest permeability and turbidity were observed in the treatment of 1.5% Dorema aucheri extract. In all edible film treatments, the antioxidant property using DPPH radicals was significant (p<0.05). The results of the evaluation of the antimicrobial activity of the film with the help of diffusion discs showed that the maximum diameter of the inhibition halo in the concentration of 3.25% was related to Escherichia coli with an average halo diameter of 5.33 mm. Average halo diameter for Pseudomonas aeruginosaand Staphylococcus aureus was reported as 4 mm and 3.99 mm, respectively. The overall results showed that the addition of Dorema aucheri extract at a concentration of 1.5% produced films that, in addition to inhibiting the growth and proliferation of bacteria, have strength and can be used for perishable food.
Food Technology
Ebrahim Taghizadeh; Mohammad Alizadeh khaled abad; Hamed Hassanzadeh
Abstract
IntroductionEdible films and coatings are suitable for fresh, semi-processed foods, and also for processed fruits and vegetables because they can increase their shelf life, protect them from the activity of microorganisms, and ultimately improve their nutritional and sensory value. In addition, edible ...
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IntroductionEdible films and coatings are suitable for fresh, semi-processed foods, and also for processed fruits and vegetables because they can increase their shelf life, protect them from the activity of microorganisms, and ultimately improve their nutritional and sensory value. In addition, edible films and coatings are able to transfer compounds that may have been added to improve the performance of the coating film and better preserve the product or have benefits for the consumer. The present research was conducted with the aim of investigating the structural physicochemical properties of whey protein concentrate smart film containing pomegranate and red grape anthocyanins and zinc oxide nanoparticles. Material and MethodTo prepare nano composite film, 10 grams of whey protein concentrate powder was added to 90 ml of distilled water. At the beginning of the production of the film, the pH was adjusted to pH = 8 with the help of 0.1 normal soda, and in order to better dissolve the isolate, the solution was heated for 30 minutes at 80 degrees Celsius to ensure denaturation. It was then placed on a magnetic stirrer. After cooling the solution, pomegranate and red grape anthocyanins were added to the solution separately according to the statistical plan. The solution was then homogenized for 10 minutes at 13,000 rpm, and finally zinc oxide nanoparticles were added to the solution according to the statistical plan and homogenized on a magnetic stirrer for 10 minutes, and then in an ultrasound bath to disperse for 10 minutes In the next step, glycerol was added to the 40% of the weight of the dry substance and placed on a rotating magnetic stirrer without heat for 15 minutes. The formed solution was aerated for 10 minutes and 25 ml of it was poured in the center of the plate (8 cm). Then the film was dried in the oven at 38 degrees Celsius and the control film was produced. After preparing the films, the color of the film samples was determined by measuring the color components L* (lightness), a* (red/green) and b* (yellow/blue) using a Hanterlab colorimeter. The thickness of the films was measured by a digital micrometer with an accuracy of 0.001 mm at 10 random points of each film. Finally, humidity, solubility and FTIR measurement tests were also performed for the prepared films. The preparation of whey protein concentrate smart composite film was investigated based on two variables: red grape anthocyanin/pomegranate anthocyanin percentage and copper oxide nanoparticle percentage. Each of which was investigated in five levels and the response surface methodology (RSM) of the central composite design was used. A total of 24 composite films were prepared and their physical and chemical properties were investigated. Also, after analyzing the data, the optimal movies were checked based on optimization and utility function by 11 Design expert statistical software. Results and DiscussionBy increasing the amount of anthocyanin and zinc oxide nanoparticles, the thickness of the layers increased up to the middle point (0.58-0.89 mm), and the largest increase in thickness was observed in samples with 1.5 cc of anthocyanin and 2% of zinc oxide nanoparticles. Also, films with low concentrations of anthocyanin (0.1-4 cc) and a high percentage of the selected range of zinc oxide (0.2-0.7%) show the highest percentage of solubility. The added zinc oxide nanoparticles increased the solubility of the films. FTIR analysis showed that the interactions between whey concentrate and anthocyanins were probably responsible for the changes in the properties of the composite layers. The utility function for each response was estimated by numerical methods and the general utility function was obtained for the optimal samples of red grape and pomegranate. For the optimal pomegranate, the obtained results include the amount of anthocyanin equal to 2.6 cc, zinc oxide nanoparticles 0.6 (weight/volume), solubility 65.37, thickness 0.64 mm, indices a, L and bwere. 27.88 0.24 and -2.01, respectively. Finally its total desirability has been reported as 0.58. The utility function for each answer was estimated by numerical methods and the general utility function was obtained for the optimal samples of red grapes such as the optimal pomegranate. For the optimal grape film samples, the obtained results include: the amount of anthocyanin equal to 1.38 cc, 3.4 zinc oxide nanoparticles (weight/volume), solubility 59.83%, thickness 0.83 mm, a, L and b indices were 27.03, 7.05 and 1.92 respectively and, its total desirability was 0.63.
